2+4i * (-7i)

There are two possible interpretations:

1. 2 + 4i * (-7i) (standard order of operations)

• 4i * (-7i) = -28 i^2 = 28
• 2 + 28 = 30 Result: 30

2. (2 + 4i) * (-7i) (if you meant the product of complex numbers)

• (2)(-7i) + (4i)(-7i) = -14i - 28 i^2 = -14i + 28 = 28 - 14i Result: 28 - 14i

Which one did you intend?